"Throughout our lives, it was common for people to stop us on the street to shake hands with Dad, telling him how much they valued and appreciated him," Noha and Razan wrote. "To many, our father was more than just a public figure — his work touched their lives powerfully and resonated with them personally. And it still does."

Noha and Razan said writing was "a compulsion" to share opinions and inspire discussion amongst his people. "Dad certainly had a pragmatic side, but in his dreams and ambitions, he was always striving for a utopian version of reality. This, we suppose, is what inspired his critical nature. It was vitally important to him to speak up, to share his opinions, to have candid discussions. And writing was not just a job, it was a compulsion; it was ingrained into the core of his identity, and it truly kept him alive," Noha and Razan wrote.

Chris McGrath/Getty Images News/Getty Images

The pair called Khashoggi "an optimist" no matter the situation. "Now, his words keep his spirit with us, and we are grateful for that. They say, 'There was a man who truly lived life to the fullest,'" the pair wrote.

Noha and Razan's most powerful passages are about their visit with Khashoggi in Virginia during Ramadan. "He introduced us to friends who welcomed him and showed us the places he frequented," Noha and Razan wrote. "Yet as comfortable as he had made his surroundings, he still spoke about how he longed to see his home, his family and his loved ones."

The day that Khashoggi left Saudi Arabia to build "a new life" in America was bittersweet, Noha and Razan wrote. "For while Dad had created a new life for himself in the United States, he grieved for the home he had left. Throughout all his trials and travels, he never abandoned hope for his country," the pair wrote. "Because, in truth, Dad was no dissident. If being a writer was ingrained in his identity, being a Saudi was part of that same grain."

After his death, the pair wrote that the family visited Khashoggi's home in Virginia. "The hardest part was seeing his empty chair. His absence was deafening. We could see him sitting there, glasses on his forehead, reading or typing away," Noha and Razan wrote.

Khashoggi wrote "so tirelessly" to better Saudi Arabia for all, the pair wrote. And they plan to keep his hope alive.

"This is no eulogy, for that would confer a state of closure. Rather, this is a promise that his light will never fade, that his legacy will be preserved within us," Noha and Razan wrote. "We feel blessed to have been raised with his moral compass, his respect for knowledge and truth, and his love."